This invention relates to a wide band angular motion sensor which serves to provide an output voltage related to angular motion of the instrument support base about a sensitive axis. More particularly the angular motion sensor is used to monitor or control small angular displacements or velocities over the wide band of frequencies.
Heretofore small angular displacements have been detected for monitoring or control purposes, but only over relatively narrow bandwidths. This has proved to be a disadvantage in applications such as monotoring earth's motion in seismological studies where small angular displacements occur over a wide bandwidth. Moreover there is a need to discriminate between translational motion and angular motion of the earth during seismic disturbances in interpreting collected data. Control systems required to sense and control small angular deviations must inherently be capable of providing flat phase and amplitude response over a wide frequency spectrum. Linear second order mechanical systems functioning in the low frequency ranges do not have the capability of error free response at higher frequencies generally. Secondary vibration modes and appreciable phase angle error characteristically cause degraded performance at higher input frequencies. Sensors capable of low frequency operation also characteristically have marginal structural features and are susceptible to error torques. There is therefore a need for a wide band angular motion sensor which introduces minimal amplitude and phase error in both anguar displacement and velocity monitoring and control applications.